Perpetual calendar



Dec. 21. 1926.

L.. P. LANDMAN PERPETUAL CALENDAR Filed August 2, 1926 5 Sheets-Sheet 1 turday unday .Hnvh 5612346.01245R OSA. 205

WVM/woo Dec. 21 1926.

l.. P. I ANDMAN PERPETUAL CALENDAR 5 Sheets-Sheet 2- -Filed August 2, 1926 @www1/hoz November "2 December 5 Z UWM/mm@ IB.: o Z505 Dec. 21 i926. 1,611,538

L.. P. LANDMAN PERPETUAL CALENDAR Fi1ed-`AuguSt 2, 192e sheets-Sheet 3 witness B, C', D or E, may either be directly op- Patented Dec. 21, 1926.

y UNITED STAT Es PATENT OFFICE.

LAWRENCE P. LANDMANQDF KEGKUK, CYWA,

PERPETUAL CALENDAR.

Application filed August 2, 1926. Serial No. 1126.542.

Y other exhibitors.

With the foregoing in view, the invention resid-es in the novel subject matter hereinafter described and claimed, the description being supplemented by the accompanying drawings. v

Fig. 1 is a front elevation partly broken away showing one form ofthe invention.

Fig. 2 is a plan view partly broken away showing the slides which, in Fig. 1 are operatively related with a face plate.

Fig. 3 is a front elevation showing a dif-1 ferent form of construction, partsbeing broken away and in section. y j

Fig. 4 is a sectional view on line 4:-4 of Fig. 3.

The form' of construction illustrated in Figs. 1 and 2 will first be specifically described. y

A, B, C, D and E designate five slides. The slideA. is provided with a column A of century numbers; the slide B is provide-d with a column B of centuryy year numbers; the slide C bears a column CYof month. names, including January and February of leap year; the slide D displays a column D of month day numbers; and the slide E can ries a column E of week day names.

The slides A, B, C, D and E are provide with key numbers A2, B2, C2, D2 and E2,

respectively, one of said key numbers being assigne-d to each of the century numbers, century year numbers, month names, month day numbers and weekday names. The key numbers for the indicia of any .column n',

posite said indicia, or offset therefrom along the length of the slide, and for purposes of clarity, certain of these indicia have been connected with their respective keys, by dotted lines, in Fig. 2.

Principle for selection of the ceg/ numbers. The key numbers arebased on the seven days of the week and each day repeating at a regular interval. The first day of the week is Sunday, and the key number 1 is assigned to Sunday. This key is also Vincreased by 7 or multiples of 7. Thus 1-,48-15-22 are all key numbers for Sunday.

Monday being the second da f of the week has 2 assigned to it for its key number. This 1s also increased by 7 or multiples of 7 Thus 2+9-16-23 are key numb-ers for Monday.

Tuesday, ldednesday, Thursday, Friday and Saturday have key numbers 3, 4i, 5, 6 and 0 assigned to them'respectively. Thus, Sat- I urdays key numbers are O-7-14-21-28, etc. The lowest key number possible is al ways used.

Applz'catz'on of the pm'acfpleaof the .key numbers to the century years, years of centena months, and the (lates of the months.

Wednesday, January 1st, 1800 `will he'cofnsidered as a starting point for conforming the centuries, years of the century, months and month dates to the key numbers assigned to each day of the week.

The month dates are first considered. Key number 1 is assignedto the first; 2 is assigned to the second; 3 is assigned to the third; 4 to the fourth; 5 to the fifth; 6to the sixth; and 0 to the seventh. 4This O is obtained by using the lowest key number. 0 and 7 are identical. The eighthv is assigned key number of 1; and so on to the end.

If January 1, 1800 was Sunday, thekey number for the month date would show the correct day'of the week. I-IowevenJ an. 1, 1800 was lVednesday the fourth day of the week. So correction mustbemade by'bringing the vtotal key numbers to d. i

This correction is madeyby applying the key numbers tothe months; and January is assignedthe key number 3. Thus, we haven 1 for the key of the month date; and 3 for the key number of the month of January; these totalling 4, the key assigned to lVe'dnesday,

Now as the month dates advance in J anuary; the key numbers for 'the month dates advance and the days of the week for J anu-` assigned. p

On January 31,l 1800 the month date will show Vkey number 3. The month name slide will also show 3. These total 6 or the key ary are controlled bythe key numbers so far number assigned to Friday. January 31, 1800 was Friday.

When February began the month dates returned to the lirst with key number 1. Jan uary ending on Friday; February began on Saturday. To obtain the key numb-er for Saturday, February is assigned the key number 6. This corrects the key numbers for February. l

Key numbers are assigned to the remaining months in the same manner. The keys for the months and month dates are permanent.

At the end of the 'year Dec. 31, 1800 is Vednesday. The Jforegzgoing key numbers applied to January 1st showed January 1st total key numbers as 4 and 'et isythe key number for lNednesday. Now as Dec. 31st was Vednesday key numbers must be corrected to show Jan. 1st, 1801 as Thursday, and a correction or 1 `must be made in theV key numbers. This is accomplished by now assigning the key numbers 'to the years or' the centuries.

As January 1, 1800 was correctV the key number is assigned to 00 for the iirst year of the century.

The 01, the ending of 1801 is assigned the key number 1. ldow for Jan. 1, 1801, we have 1 tor the key numberoi the month date, 3 for the key number of the month; and 1 for the key number or the year of the century. A total ot' and this is the key number of Thursday. The key numbersare now correct for the year- 1801 and the entire year is handled the same as was 1800.

As this occurs 'atthe end or every year, the key numbers are arranged as shown. However every leap year the key numbers for the years of the century are advanced two instead of one to take care of the extra day in leap year. This advance olf two also advances January and February two instead ot one and as the eXtra day occurs 'at the end of February special months with key numbers are arranged for Y January and February of leap years. These months having one deducted from their regular assigned key numbers. In 'other words the key nun bers for January and February or a lea'o year are one less than the key numbers of January and February when not a leap year. It has been previously shown that the key number for January wasA 3, and the key number for February was 6 when not-,a leap year.

For a leap year, the key number or J anuary is 2. and the key number' for February is From this, it will be understood that the key numbers for January andjF'ebruary of leap years are one less than the key numbers assigned to these months when nota leap year.

The keys are now correctfor the entire 19th century. (Years 180041899.) Y

On completing the 19th century, slide B has made a complete revolution and start at vmade on the century year.

l00 for the 20th century. It must be noted that the key number for 99 is L1; and that the key number of 00 is 0. As 0 and 7 are identical this is an increase of three instead of one. (1900 not a leap year.)

To correct this advance of three instead ol' one, the key numbers are now applied to the century years.

As the 19th century was correct the number 0 is assigned to 18 which covers years 15300-1899. As stated before 0 and 7 are identical, the extra two are Leducted from 7. Thus, the key number or is lassigned to 19 for the years 190041999 This century is non7 corrected. l

However, the year 2000 is a leap yea and the saine vcondition that lmppened changi x1' from 1899 to 1900 happens when changing7 from 1999 to 2000. So c rrection is again This time only one is subtracted on account oit 2000 being a leap yea-r. This gives 20 the key number of e.

At the end of the 21st century, the condition is identical with the condition that existed at the end of the 19th century so the key number of 2 is assigned to 21. numbers are assigned to remaining century years in same manner.

This explanation hasnow covered a j ieiicd of L years and every /100 years the calendar repeats itself. Thus Jan. 1, 1800 is identical to J an. 1, 2200. Both are llednesday. By applying the foregoing over and over the key numbers produce a perpetual Calenda'.

Co-operable with the slides A, B, C, D .u E is a face plate P having slots S through which said slides pass, so that portions of t-he latter are behind the race plate. This face plate is also provided with openings 0 "to display the indicia oit' the columns Eff, B.

C, D and E. The race plate is with additional openings 0 to key numbers A2, B2, C2, D2 and E2.

The slides may be relatively adjusted te expo-se a complete set ofthe century, cent year and month day numbers and month anu week 'day names, so as to represent any se lected date. For instance, in Fig. 1. slides A and B have been adjusted to represent the year 1926; the slides C and D hz w been adjusted to indicate July iith, and the slide Fi has been moved to show that July 1926 falls upon Sunday. The slides A, lf3, C and D may obviously be set properly without taking their key numbers into consideration. However.l the week day name to appear in the opening 0 in front of the slide F, is the unknown element. However, in order to properly set said slide E, it is only necessary to add the key numbers or the slides A, B, C, and D, appearing in the opening 0. Adding these key numbers, we find that they total 15. Hence, by setting the slide E so that 15 appears in the co-related opening also formed display the llt) , We find that Sunday. appears in the adjacent opening 0. We are thus informed that July 4, 1926 falls upon Sunday. This is only one example of the manner of using the invention, but such example will sulce, it being of course remembered that in leap years, when dealing with January or February, the properly designated names or abbreviations of the slide C, must be set at the opening O.

The slides A, B, C, D and E need not in all instances be used, but other equivalent changeable exhibitors could be employed, such as rotary disks, cylinders, endless bands and the like. In this connection, attention is invited to Figs. 3 and 4 which disclose endless bands A3, B3, C3, D3 and E3, corresponding to the slides A, B, C, D and These bands are trained around suitable rollers R and said bands and rollers are dis-y posed in a suitable casing P having the requisite openings O2 and 03. Portions of certain of the rollers are exposed so that said rollers may readily be rotated to adjust the bands as occasion may demand.

While excellent results may be obtained i from the disclosure herein given, it is tobe understood that such disclosure is for illustrative purposes, and that Within the scope of the invention as claimed, numerous variations may be made. For instance, key numbers here assigned maybe changed by assigning ditterent key numbers to the daysY of the Week. Key numbers assigned to slide A can be added to slide C. This would give i'our sets of months for slide C' and no key numbers for slide A. Same applies to slides A and B,

For a calendar of one year period, keys of A, B, and C may be added and shown as months. In this case a small device of slides could contain the data and the device be of pocket size, as the data for A and B Would be eliminated. V

Also a calendar for a tive year period, a

' ten year period, etc., can be made likewise.

Further: To slide A, key numbers 21 can be added. Then key numbers of slides B, C and D can be subtracted from 7. Now if the totals of B, C and D are subtracted from A, the number Will be the correct day of the Week. Example- Date 19 26 May 1 Key i 4 1 Total of keys 14. To 5 add 21. Subtract 4 from 7 subtract 4 from 7 (May); subtract 1 from #7. Result 26 3 3 6 Add the lastthree key numbers and subtract them from the 1st number. v

' E Mala-26 less 12 or 14 which is same as ey number result lirst shown. Key numbers may be altered in one part and balanced in other parts.

The starting point in this explanation Was Jan. 1, 1800, l/Vednesday. It the starting point is changed to some other time, the key numbers Will also be changed. For example: Had the starting point been Jan. 1,

`having indicia representing centuries, century years, month names and month days, permitting said exhibitors to be set to represent any desired date, keys assigned to said indicia and exposed to View by sett-ing of said exhibitors, an additional changeable exhibitor having Week day names to disclose the day on Which any date fell or will all, and keys on said additional exhibitor constituting the results of mathematical calculations With the keys of the first named exhibitors, whereby upon setting the iirst named exhibitors for any date, performing the predetermined mathematical calculation with the keys thus exposed and setting the additional exhibitor to expose the key duplicating the result of said calculation, the day of the week for the date setting Will be disclosed.

A calendar comprising ve changeable exhibitors; century numbers, century year numbers, month names, month day numbers, and Week day names on said exhibitors respectively; key numbers on said exhibitors allotted one to each century number, century year number, month name, month day number and Week day name; and a face plate apertured to expose a full lset of the aforesaid names and numbers to represent any selected date; the key number for the Week day name of any such set being the total ot the other key numbers of said set.

t.) may 'E In testimony whereof I have hereunto aitl fixed my signature.

, LAVRENCE P. LANDMAN, 

